Also found in: Thesaurus, Medical, Acronyms, Idioms, Encyclopedia, Wikipedia.

rad 1

A unit of energy absorbed from ionizing radiation, equal to 100 ergs per gram or 0.01 joule per kilogram of irradiated material. It has been replaced as a standard scientific unit by the gray.

[r(adiation) a(bsorbed) d(ose).]

rad 2

adj. Slang
Excellent; wonderful.

[Short for radical.]

rad 3

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Units) a former unit of absorbed ionizing radiation dose equivalent to an energy absorption per unit mass of 0.01 joule per kilogram of irradiated material. 1 rad is equivalent to 0.01 gray
[C20: shortened from radiation]


symbol for
(Units) radian
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014



n. Physics.
a unit of absorbed dose equal to 0.01 Gy. Compare dose (def. 4).
[1915–20; shortening of radiation]



1. Informal. a radical.
2. Slang. fine; wonderful.
[1820–30; shortening of radical]




1. radical.
2. radix.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


A unit used to measure energy absorbed by a material from radiation. One rad is equal to 100 ergs per gram of material. Many scientists now measure this energy in grays rather than in rads.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


1. A unit of radiation absorbed from a radioactive source.
2. A short form of radian, a unit of measure for plane angles. See centrad.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.rad - a unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material
radioactivity unit - a measure of radioactivity
2.rad - the unit of plane angle adopted under the Systeme International d'Unites; equal to the angle at the center of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)
angular unit - a unit of measurement for angles
milliradian - a unit of angular distance equal to one thousandth of a radian
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in classic literature ?
Rad wanted to do it all alone, but Koku said he was like a baby now."
I tell ye what, men, old Rad's investment must go for it!
"Then I must get some from old Rad;" and he rose to go aft.
Four years ago, the RAD was bankrupt and threatened with closure.
RAD's contribution consisted of the ETX-2i, with its carrier grade vCPE-OS operating system, which combine advanced NID and vCPE functionalities.
Also, up to 688 ports can be supported, claims RAD, and the DXC-100 can grooms traffic between various voice and data networks in order to reduce the number of ports required on co-located service platforms or inter-network facilities between service providers.
"For mainstream uCPE white boxes to transition to the carrier domain, there are several performance, functional, and operational issues that need to be resolved before they can deliver on their agility and automation promise," noted Ilan Tevet, RAD's VP Marketing and Business Development.
Its objective will be to promote sales and develop business opportunities throughout the region, according to the new general manager of RAD Australia.
Sunrise selected RAD's performance monitoring overlay solution as an add-on to its existing network.
"As the leader in the EAD market, it is only natural that RAD would extend its offering to truly cover any access requirement," said Ilan Tevet, RAD's Vice President of Marketing and Business Development.
The software uses RAD tags, where podcasters can mark their audio files at certain points.